The sun-shading umbrellas used on streets or in a café have large covering area. Due to the large surface and the thick frame of the umbrellas thereof, a distance between an umbrella erection site and a nearby wall is necessary for preventing contact therebetween. These sun-shading umbrellas therefore have to be mounted away from the wall and into a sidewalk, hindering people walking by. It is a further disadvantage that shopkeepers retrieving the umbrellas after business may also cause inconvenience to people walking by.
Moreover, the large sun-shading umbrellas of the prior art do not have a control device that adjusts the height and the expansion/contraction of the umbrellas simultaneously. Also, they do not have a control device that rotates the main shaft axially. It is a further disadvantage of the conventional sun-shading umbrellas that there does not exist a control device for adjusting the angular orientation of the umbrellas surface.